9 Jan 2019

Sega 315-5298 GAL22V10 alternative (System 16B)

While working on the System 16B multi I soon discovered some romboards (171-5704/171-5521/171-5797) contained a PLS153 chip noted 315-5298 used for tiles banking. Unfortunately I own only one System 16B game (Shinobi) and it runs on 171-5358 romboard which is the simplest one and lacks the PLS153 chip (not needed as early games had less tiles). Fortunately collector lapsus sent me one for dumping (side note: PLS153 can't be read protected/locked).

Then I converted them for a GAL22V10 (thanks to lapsus again for probing the PLS153 pinout/signal names).
GAL16V8 is unfortunately 1 output short and I have no GAL18V10 in my parts stock (was it ever used on any arcade PCB?).

It made perfect sense to me (data bits are latched to create higher address lines).

Testing on my custom multi romboard revealed it worked pefectly fine.

lapsus confirmed it to be working on OG hardware too by using a small adapter to reroute a couple of signals as the PLS153 is DIP20 and GAL22V10 is DIP24:
- ground by connecting pin 12 (GAL22V10) to 10 (PLS153 socket)
- generated a15 line from pin 14 (GAL22V10) to pin 9 (PLS153 socket)
GAL22V10 pin 1 has to be aligned to PLS153 socket pin 1, pins 11/12/13/14 stick out:

Hi Caius, glad to see you still read me.I didn't know you dumped that chip already.Anyway I was more interested in showing the method and providing the source files so people can see equations and adapt them to other devices if they like.